The present invention relates generally to integrated circuit devices and, more particularly, to programmable fuse/non-volatile memory structures (and arrays) using externally heated phase change material.
Electrically programmable fuse (eFUSE) devices have many practical applications such as, for example, redundancy implementation in memory arrays, field programmable arrays, voltage trimming resistors/capacitors, RF circuit tuning, electronic chip identification, usage tracking/diagnostic data logging, remote disabling of a device/car that is reported stolen, read only memory (ROM), etc. Existing eFUSE technology is based on various different techniques such as, for example, electromigration (IBM), rupture (Infineon) and agglomeration (Intel). However, each of these existing fuse technologies are “one-shot,” in that once the fuse is blown, it cannot be returned to a conducting state. Moreover, such devices occupy relatively large areas, involve large amounts of power/current, and are very slow to program (e.g., several microseconds).
On the other hand, reprogrammable fuses utilizing chalcogenide materials (and indirect heating through a resistive heater) are described in U.S. Pat. No. 6,448,576 to Davis et al. However, such chalcogenide fuse materials emit large amounts of heat, and it is estimated that switching currents needed to produce the required programming heat are on the order of about 15 mA. Under this assumption, a required heater current of 15 mA would in turn result in a design that is inconveniently large, requiring a driver FET width on the order of about 15 microns.
Accordingly, as eFUSE technology develops, it will be desirable to be able to address existing concerns pertaining to higher performance, including factors such as: reducing the device area taken up by the fuse, cope with the “sunsetting” of the non-standard high voltages/currents required by existing programmable fuse devices, the desirability of having multishot reprogrammable fuses, and enhanced speed, among other aspects. In addition to the general improvement of eFUSE technology, there is also the issue of contamination susceptibility of the substrate (e.g., silicon) material from the materials used in eFUSE technology, as well as effects on temperature sensitive insulating materials (e.g., low-K SiCOH) in the integrated circuit device.